Fitness-For-Service
The Fitness-For-Service methodology is a multidisciplinary approach aimed at rationally determining if a pressure component can be operated, and how long, under one or several damage mechanisms. Hence, equipment Maximum Allowable Working Pressure (MAWP) and residual life are the main purpose of a Fitness-For-Service assessment.
A FFS evaluation usually involves diverse technical figures: NDT personnel, material, process and integrity engineers, FEM/FEA analysts.
From one of the first standards introduced in the petrochemical sector (API RP 579), the Fitness-For-Service method has rapidly grown in popularity in other fields of the industry with the publication of the API 579-1 / ASME FFS-1 by a joined ASME/API committee.
Many studies demonstrated how the FFS approach is cost-effective: it can prove equipment safe operation margins, avoiding users all the additional costs due to failures and forced outages, and can provide a rational basis for maintenance management.
Typical scenarios that highlight Fitness-For-Service effectiveness:
“We discovered a metal loss well under the design limits on a pressure vessel during periodic inspections, can we still operate it? At what conditions? Is a recontrol mandatory? When?”
“NDTs reported there’s a flaw on a pressure member, can we still operate it? How long? What’s the MAWP?”
“A pipe was mechanically dented and it’s visibly deformed, can we wait until next programmed stop?”
“We have a pressure vessel that was caught in a fire, can we put it back into service?”
“Our superheater finished its design creep hours, can we extend its operating life?”
The FFS methodology can also be harmonized with the European global and National jurisdiction dealing with the mandatory periodic inspections on pressure vessels and piping, thus providing a sound basis for the integrity evaluation of the equipment.
In Studio Scano we are convinced that the Fitness-For-Service approach, along with a thorough investigation of the potential damage mechanisms, the proper NDTs, and the most recent analysis tools and techniques, can be a valuable service for all the companies dealing with aging pressure plants.
